The primary hyperoxalurias (PH) are caused by deficiencies of the hepatic enzymes alanine: glyoxylate aminotransferase and glyoxylate reductase. The diseases have significant morbidity and mortality caused by endogenous oxalate overproduction, with deposition of excess oxalate as either kidney stones or nephrocalcinosis. Each disease has marked clinical heterogeneity, apparently unrelated to the degree of enzyme deficiency, preventing genotype/phenotype correlations and therefore limiting predictions of disease outcome. Some of the clinical variability may be related to genetic and/or acquired differences in either the renal handling of oxalate or renal production of modulators of stone disease. The Iong-term goals of this project are to culture proximal tubular cell lines from patients with PH to provide a valuable resource for scientists studying the effect of this disease on the kidney. [unreadable] [unreadable] The specific aims of this project are as follows: [unreadable] (1) To use microarray technology to compare mRNA expression in proximal tubular cells of PH patients with proximal tubular cell lines from normal subjects (2) To use microarrray technology to compare mRNA expression in proximal tubular cells from patients and controls cultured in the presence and absence of oxalate (3) To use microarray technology to look for differences in proximal tubular mRNA expression from pH patients with identical genetic defects but with different clinical phenotypes. Primary cultures of proximal tubular cells harvested from urine samples of patients with primary hyperoxaluria will be grown in culture, mRNA isolated from these cell lines and from normal controls prepared in the same way, will be reverse transcribed and cRNA prepared labelled with biotin prior to hybridization against human U133A Affymetrix microarray. Genes, which show differences in expression between patients and controls, as detected by fluorescence quantitation, will be identified by reference to their location on the microarray. Quantitative data for specific gene expression will then be obtained in a wider number of patients and control samples by RT-PCR. This project offers a non-invasive means of investigating the effect of primary hyperoxaluria on the kidney and may define some of the mechanisms by which pH develops and progresses. By understanding why the disease progresses at different rates in patients with the same genetic abnormality, it may then be possible to devise strategies to slow down or prevent the clinical consequences of the disease. [unreadable] [unreadable]